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A gold rock.
A Gold rock is a protruding rock containing gold ore. A player with a Mining level of 40 or higher can mine gold ore from rocks found in various mines, granting 65 Mining experience for each ore mined.
Gold rocks can be found in many mines and mining sites throughout RuneScape.
Gold ore, like all other mined rocks, respawns at a rate directly proportional to the number of people in the rock's RuneScape world. If the world is empty, the ore respawns in 2 minutes; if it is full (with 2000 players), it respawns in 1 minute. You will notice that once mined the rock will turn a darker grey colour.
When you are mining a gold rock, the chance that you get an emerald, ruby, saphire or diamond are higher than when mining other rocks.